Try to get device vendor_id from the PCI bus
Try to get device vendor_id from the PCI bus

The (currently provisional) OpenCL 3.0 specification has finally
clarified the usage of the CL_DEVICE_VENDOR_ID field: for vendors with a
registered PCI vendor ID, this should be used here.

If no PCI vendor ID is defined, a Khronos-specific vendor ID
should be registered with them, which will then be used as vendor ID
across Khronos APIs (e.g. in Vulkan too).

Rather than making up our 'pocl' based vendor ID, we can try and get the
vendor ID of the PCI root device, which in my limited testing experience
matches the vendor ID of the CPU (i.e. it's 0x8086 for Intel and 0x1022
for AMD).

Oblomov/pocl,franz/pocl,franz/pocl,pocl/pocl,Oblomov/pocl,franz/pocl,franz/pocl,pocl/pocl,franz/pocl,pocl/pocl,Oblomov/pocl,Oblomov/pocl,Oblomov/pocl,pocl/pocl,pocl/pocl